The present invention generally relates to a compressor and more particularly, to a hermetic compressor for use in a cold storage chamber, freezing chamber or the like.
It has been a recent trend that an improvement in the compression efficiency has been required for a reciprocating type cooling medium compressor to be employed in a cooling system such as a cold storage chamber, freezing chamber or the like.
As one technique for meeting such a requirement, there has been conventionally proposed a construction in which the disadvantage that a suction gas is heated and expanded in the compressor so that the suction gas with a low density is drawn into a cylinder and eliminated, whereby reduction in density of the suction gas is prevented so as to provide higher suction efficiency.
By way of example, one known arrangement is disclosed in U.S. Pat. No. 4,370,104 in which, by mounting a suction pipe on a casing, a suction muffler having its inlet portion facing an outlet of said suction pipe, and formed into a horn shape is provided within the casing, so that said suction muffler is connected to a suction plenum. Another example disclosed, for example, in U.S. Pat. No. 4,531,894, is so arranged that, with a suction pipe being led up to a suction muffler, an outlet portion of said suction muffler is mounted on a cylinder head.
In the above conventional arrangements, however, since suction pipes generally made of copper are employed, such suction pipes are heated through heat exchange with respect to the casing of the compressor, with consequent heating of the suction gas. Therefore, arrangement is so made that the heated suction gas is not easily returned by returning most of or all of the suction gas into the suction muffler. However, when the fact that the suction gas is heated by the suction pipe, is taken into account, sufficient improvement of the compression efficiency has not been available.